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"Reference" TDA1541A DAC with I2S-BUS architecture

Surface Finish for future PCB´s

  • ENIG - Electroless Nickle/Immersion Gold

    Votes: 93 48.7%

  • Immersion Silver

    Votes: 54 28.3%

  • Immersion Tin

    Votes: 24 12.6%

  • OSP - Organic Solderability Preservatives

    Votes: 20 10.5%
  • Total voters
    191
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#1,303
I wonder if anyone can help me with a problem with Oliver's 3-way Salas shunt regulator board. I assembled it well over a year ago but put it aside because procrastination is what I'm best at. Digging it out last week, I remember why - the voltage on none of the rails goes low enough. For testing, I'm using a 19v DC input on each of the +/-5v and the -15v. Full (click-stopping) adjustment of the pot gets the output down to +5.3, -6.5 and -18v.

I readily admit that I don't properly understand the circuit. Can anyone give me any pointers as to where I might start looking? Many thanks.

Dave
 
#1,307
wlowes said:
. . . do all of the LEDs light up brightly?
Click to expand...

Thanks for the reply. Yes, they light up much as I'd expect; the drop across each is ~1.9v. After reading Salas' notes and putting a resistor on the output to draw ~50ma, I replaced the 500R trimpot in the -15v circuit with a 1K pot and was able to swing from well below -15v to above with the final setting roughly in the middle. (I don't have parts to hand for the pots in the +/-5V boards so can''t as yet try the change on them.)

BUT - there's always a but - I noticed that the output starts at about -15.7 volts and takes ten minutes or more to settle down to -15v. Is that normal? Doesn't seem right to me.

Dave
 
#1,308
Hi Dave, Im not sure, but mine tended to drift until I used shorter wire. It was oscillating a bit so I cut the wire leads to the dummy load and it was stable. Can you check with oscilloscope? If its stable I wouldn't be too concerned, but I am not an expert so maybe someone else can chime in, or ask Salas in his build thread.
 
#1,315
:scratch2:Many thanks for the Red Baron v5 board Saulius. It is all built up.

Sadly though, I have no sound :scratch2: Perhaps Oliver can help

I still have not much clue about which board is at fault - the Teradak i2s converter, the Red Baron, or the Tubizator....

I have checked that the -15, -5 and +5 are present on the chip itself :checked:, have checked that the new design i2s attenuator has power :checked:(although it's 4.5v as I haven't yet made up a 3.3v regulator. Shouldn't it still work?)

My Tubizator valves are glowing :checked:, and have the required voltage :checked:. I have used the 75R resistors on the underside of my v1 tubizator pins. Is that OK?

How do I check if the i2s is present at the DAC? How do I check if audio signals are coming from the Red baron Board to the output stage?

Many thanks
Lucas
 
#1,319
Suspecting my Teralink X2, I have checked my DC voltages at the i2s input to the Red Baron board with music playing from iTunes. I have:

BCK: 2.7vDC, 0.004vAC

WS/FS: 2.5vDC, 0.34vAC

DATA: 1.9vDC (fluctuating 1.9v - 1.95vDC) and 0.4vAC (fluctuating 0.4v - 0.45vAC)

Is this normal? Thanks
 
#1,320
I am now convinced that my issue is i2S.

I touched the DATA and WS pins together, and got (highly distorted) music.

So, I have UFL pads soldered in place, but I'm not using them yet.

I have them wired as with my old TDA1541 board: GREEN to data, BLUE to FS/WS and BROWN to BCK, but it's not working. Am I missing something? Does the GND need to go just to the Red Baron Board i2s gnd, or somewhere else too?
 
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